727 was originally going to be introduced in an overlay plan, to overlay 813. At the time, overlays were a new concept and since overlays result in mixing area codes within the same area (issuing the new code to new numbers) requiring 10-digit dialing and were often met with public resistance at the time. With this in mind, GTE (now part of Verizon), the dominant carrier in most of the Tampa Bay Area, switched the proposal to a split plan.

The split largely followed county lines, with the notable exception of Oldsmar, most of which stayed in 813. Oldsmar's trunk is wired into the Tampa line, and it would have been too expensive for GTE to rewire it.